Walls constructed of concrete blocks are well known in the field of construction and have been extensively used for walls both above and below ground. Walls constructed in this manner are generally capable of supporting residential and light commercial structures and are relatively inexpensive to manufacture. In order to construct a concrete wall, individual blocks are laid end-to-end and successive rows or courses are stacked thereon. Mortar between each adjacent block and row secures the wall together. These walls are such that they have excellent compressive strength to support structures placed upon them. However, these walls are inherently weak with respect to lateral loads and are particularly susceptible to cracking from water pressure. This inherent weakness is attributable to the structural characteristics of the walls themselves and the mortar joints at which they are connected. Specifically, the mortar joints are weak in tension and when subject to tensile forces, tend to separate relatively easily.
Water penetrating deeply into the soil adjacent a basement wall can cause substantial lateral movement of the soil and pressure against the wall. Over a period of time, block walls may be seen to develop diagonal cracks at their ends and vertical cracks near their centers. Such cracks can admit water from the surrounding soil and if left untreated, can progressively widen and eventually facilitate collapse of the entire wall with resultant damage to the structure supported on it. In addition to developing cracks, block walls typically either tilt or bow inwardly and such bowing or tilting steadily worsens under the weight of the overlying structure.
These problems are not only limited to walls constructed of concrete blocks. These problems are also inherent in solid concrete structures. Such concrete structures include, but are not limited to, solid concrete walls, pillars, columns, and support beams, such as those used in bridges or overpasses.
One of the traditional methods of repairing the cracks and relieving the external pressure is to drill holes and provide for channeling of the water away on the inside. Yet another method is to fill the cracks by injection of an epoxy resin. Although these methods help to control further water from entering the cracks, they do not prevent the walls from further cracking or bowing.
Yet another means of fixing cracks in concrete structures is to bond carbon fibers thereto, as disclosed in commonly owned U.S. Pat. No. 6,692,595. Carbon fibers are typically provided in a mesh-type structure such that an epoxy used to bond the fibers to the wall wholly encompass the fibers. Although carbon provides great tensile strength, it appears that in some installations it is strong enough to actually pull the concrete loose from the wall.